Creating AWS RDS Database with Terraform (4/5)

RDS MariaDB Database and Resource Tags

This is the continuation of a Terraform demo to create a VPC in AWS with an EC2 instance connected to MariaDB database running in RDS (Amazon Relational Database Service) using a single Terraform plan.

Operating System and software configuration is done using Ansible after the infrastructure has been created.

Prerequisites and source code:

• Terraform Setup and AWS VPC Subnet Creation (1/5)
• VPC Subnet Routing and Internet Access with Terraform (2/5)
• AWS Route 53, AMI Lookup and EC2 Creation with Terraform (3/5)

Configuring an RDS MariaDB Database with Terraform

AWS RDS databases are ready-to-use databases backed by AWS experience and with easy-to-use administration tools.

Best Practice: Use Cloud Services When Possible
Focus all your resources and energy on configuring and developing what is really disruptive and unique. Databases, Email servers, DNS servers, and Queues are now a commodity.

Most of the time if you need full control of those services and If you don’t have millions of customers there is a big probability that you have a wrong design.

The AWS RDS database is fully configured in the terraform.tfvars file.

Be aware of the password in clear text in terraform.tfvars. It will also show in terraform.tftstate and terraform.tfstate.backup.  Currently, the recommended action for passwords in Terraform files is to change them after resource creation using a different tool (AWS CLI, AWS Console, Ansible, DB Client …). A changed password in Terraform doesn’t trigger a resource property change.

#------------------------
# RDS INSTANCES
#------------------------

  #------------------------
  # MariaDB PRO 01
  #------------------------
  aws_rds_mariadb_pro_pub_01 = {
    identifier              = "ditwl-rds-mariadb-pro-pub-01"
    allocated_storage       = 20 #GB
    storage_type            = "gp2"
    final_snapshot_id       = "ditwl-rds-mariadb-pro-pub-01-final"
    skip_final_snapshot     = false
    engine                  = "mariadb"
    engine_version          = "10.2.11"
    instance_class          = "db.t2.micro"
    password                = "**************"
    username                = "ditwlRDSPROdb01" #Start with a letter. Only numbers, letters, and _ accepted, 1 to 16 characters long
    availability_zone       = "us-east-1a"
    backup_retention_period = 5
    #db_subnet_group_name   = See var aws_rds_sn_pro_01["name"]
    multi_az                = false
    vpc_security_group_ids  = ""
    parameter_group_name    = ""
    allow_major_version_up  = false
    publicly_accessible     = true
    tag_private_name        = "ditwl-rds-mariadb-pro-pub-01"
    tag_public_name         = "ditwl-rds-mariadb-pro-pub-01"
    tag_app                 = "mariadb"
    tag_app_id              = "mariadb-01"
    tag_os                  = "rds"
    tags_environment        = "pro"
    tag_cost_center         = "ditwl-permanent"
  }

  #------------------------
  # RDS Security Group
  #------------------------
  aws_sg_rds_mariadb_pro_pub_01 = {
    sec_name        = "ditwl-aws-sg-rds-mariadb-pro-pub-01"
    sec_description = "ditwl - MariaDb server access rules - Pub, Env: PRO"
    allow_all_outbound = false
  }
    #------------------------
    # Allow access from my Instances to DB port
    #------------------------
    aws_sr_rds_mariadb_pro_pub_01_instances_to_db_port = {
      type              = "ingress"
      from_port         = "3306"
      to_port           = "3306"
      protocol          = "tcp"
      #source_security_group_id module.aws_sec_group_ec2_default.id
      description       = "Access from Instances to DB port"
    }

aws_rds_pro_mariadb_01.tf is used to create the security group, assign the security rule, and launch the database.

#----------------------
# RDS MariaDB
#----------------------

# SECURITY
  # Group
  module "aws_sg_rds_mariadb_pro_pub_01" {
    source      = "./modules/aws/security/group"
    vpc_id      = module.aws_network_vpc.id
    name        = var.aws_sg_rds_mariadb_pro_pub_01["sec_name"]
    description = var.aws_sg_rds_mariadb_pro_pub_01["sec_description"]
  }

  # Rules
  # Access from instances in group aws_sec_group_ec2_default to DB Port
  module "aws_sr_rds_mariadb_pro_pub_01_instances_to_db_port" {
    source            = "./modules/aws/security/rule/source_group"
    security_group_id = module.aws_sg_rds_mariadb_pro_pub_01.id
    type              = var.aws_sr_rds_mariadb_pro_pub_01_instances_to_db_port["type"]
    from_port         = var.aws_sr_rds_mariadb_pro_pub_01_instances_to_db_port["from_port"]
    to_port           = var.aws_sr_rds_mariadb_pro_pub_01_instances_to_db_port["to_port"]
    protocol          = var.aws_sr_rds_mariadb_pro_pub_01_instances_to_db_port["protocol"]
    source_security_group_id = module.aws_sg_ec2_default.id
    description       = var.aws_sr_rds_mariadb_pro_pub_01_instances_to_db_port["description"]
  }

module "aws_rds_mariadb_pro_pub_01" {
  source = "./modules/aws/rds/instance"

  identifier              = var.aws_rds_mariadb_pro_pub_01["identifier"]
  allocated_storage       = var.aws_rds_mariadb_pro_pub_01["allocated_storage"]
  storage_type            = var.aws_rds_mariadb_pro_pub_01["storage_type"]
  final_snapshot_id       = var.aws_rds_mariadb_pro_pub_01["final_snapshot_id"]
  skip_final_snapshot     = var.aws_rds_mariadb_pro_pub_01["skip_final_snapshot"]
  engine                  = var.aws_rds_mariadb_pro_pub_01["engine"]
  engine_version          = var.aws_rds_mariadb_pro_pub_01["engine_version"]
  instance_class          = var.aws_rds_mariadb_pro_pub_01["instance_class"]
  password                = var.aws_rds_mariadb_pro_pub_01["password"]
  username                = var.aws_rds_mariadb_pro_pub_01["username"]
  availability_zone       = var.aws_rds_mariadb_pro_pub_01["availability_zone"]
  backup_retention_period = var.aws_rds_mariadb_pro_pub_01["backup_retention_period"]

  # Workaround for dependency. We need Terraform to wait for aws_rds_sn_pro_01 creation before the RDS DB can use it.
  db_subnet_group_name    = module.aws_rds_sn_pub_pro_01.id #aws_rds_sn_pro_01["name"]

  multi_az                = var.aws_rds_mariadb_pro_pub_01["multi_az"]
  vpc_security_group_ids  = [module.aws_sg_rds_mariadb_default.id,module.aws_sg_rds_mariadb_pro_pub_01.id]
  publicly_accessible     = var.aws_rds_mariadb_pro_pub_01["publicly_accessible"]

  #parameter_group_name    = aws_db_parameter_group.rds_pos_96_db_parameter_group_01.id
  allow_major_version_up  = var.aws_rds_mariadb_pro_pub_01["allow_major_version_up"]
  tag_private_name        = var.aws_rds_mariadb_pro_pub_01["tag_private_name"]
  tag_public_name         = var.aws_rds_mariadb_pro_pub_01["tag_public_name"]
  tag_app                 = var.aws_rds_mariadb_pro_pub_01["tag_app"]
  tag_app_id              = var.aws_rds_mariadb_pro_pub_01["tag_app_id"]
  tag_os                  = var.aws_rds_mariadb_pro_pub_01["tag_os"]
  tags_environment        = var.aws_rds_mariadb_pro_pub_01["tags_environment"]
  tag_cost_center         = var.aws_rds_mariadb_pro_pub_01["tag_cost_center"]
}

A workaround is used to create a dependency between the RDS subnet group and the RDS database. See RDS subnet group creation in part II (VPC/RDS Sub Nets).

db_subnet_group_name = module.aws_rds_sn_pub_pro_01.id

In order to launch the RDS database the subnet needs to exist, we provide the name of the RDS subnet using the output ID of the RDS subnet as source, this way Terraform is forced to create the RDS subnet first in order to evaluate the output ID.

Tag the RDS instance with all the needed identifiers.

Best Practice: Tag all your AWS Resources
Tags can be used to identify resources, split costs between cost centers, and for further configuration, provisioning, and monitoring with dynamic inventories using Ansible or other tools. See AWS Tagging best practices.

Continue the Terraform and Ansible demo, see:

• Terraform AWS Tutorials
  • Terraform Setup and AWS VPC Subnet Creation (1/5)
  • VPC Subnet Routing and Internet Access with Terraform (2/5)
  • AWS Route 53, AMI Lookup and EC2 Creation with Terraform (3/5)
  • AWS RDS MariaDB Database and Resource Tags with Terraform (4/5)
  • EC2 Instances and Resource Security with Terraform (5/5)
• Ansible Tutorials
  • Using Ansible for Terraform Managed AWS Infrastructure